The purpose of this study was to apply the supported liquid membranes with strip dispersion ((SLM-SD) technology on the separation and concentration of two rare earth metal ions, dysprosium and neodymium, from waste streams of the magnet industry. In this work, D2EHPA, Isopar-L, and aqueous neodymium and dysprosium nitrate solutions were used to be the extractant, diluent and feed solutions respectively in order to evaluate the separation efficiency of the support liquid membranes with strip dispersion process. Some parameters influencing on the permeability of dysprosium and neodymium ions including the acidity of feed solutions, flow rate in tube side, extractant concentrations, as well as stripping agent concentrations were investigated in detailed. Results indicated as acidity of feed solutions increased, the permeability of neodymium and dysprosium ions decreased. Besides, in weak acid condition, as the flow rate in tube side increased, the permeability of two ions increased. But in strong acid condition, there was no relationship between the flow rate in tube side and permeability of two ions. Additionally, as extractant concentrations increased, the permeability of neodymium and dysprosium ions increased. There was no relationship between stripping agent concentration and permeability. .In separation of neodymium and dysprosium ions, pH 1.15 in feed solutions, feed side flow rate 0.04m/s, 5mM D2EHPA dissolved in isopar-L, and 2M nitric acid as strip solution were used. The permeability of dysprosium ions was 6.75×10-6 m/min and 95.14% recovery was achieved. In this process, 300 mg/L Dy3+ were concentrated to 1420 mg/L after 4 hours operation. Enhancing D2EHPA concentration to 50mM in the second process, permeability of neodymium ions was 1.26×10-5 m/min and 300 mg/L neodymium ions were recovered. A 92.62% recovery and concentrated 1379 Nd3+ mg/L can be reached after 4 hours operation. The batch extraction experiments were carried out to determine the equilibrium constant for the formation of the extracted complexes. The SLM-SD transport model was presented in terms of the mass transfer behavior in the hollow fiber, chemical reaction of the metal and extraction on the feed-membrane interface, and diffusion of metal complex on the membrane phase. The kinetic parameters were calculated and successfully used to describe the permeation of two kinds of ions.

Strip dispersion;supported liquid membrane;dysprosium;neodymium